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Biomedical subjects

J L Davis

Publications and source records attributed to J L Davis.

At least 127 records · Page 7Linked to original sources
PubMed1989

Double-contrast computed tomography of the shoulder.

As a modality for the study of abnormalities of the shoulder, double-contrast computed tomography (CT) is accurate, is relatively easy to perform, and requires only a low dose of radiation. The results can be extremely helpful in preoperative planning. In this study, CT images were obtained for 247 patients who had undergone routine double-contrast shoulder arthrography. Abnormalities shown on CT images included glenoid labrum attenuation and tears, glenoid fractures, loose joint bodies, intracapsular staples, intra-articular screws, adhesive capsulitis, rotator cuff tears, peritendinitis calcarea, biceps tendon tears, and capsular abnormalities. In the 41 cases in which surgical correlation was available, all of the confirmed abnormalities had been identified on double-contrast CT images. Of the patients with rotator cuff tears, 80% had other abnormalities of the shoulder, and 48% had glenoid labrum tears. Of the patients with peritendinitis calcarea, 40% had glenoid labrum tears, and 33% had rotator cuff tears. Double-contrast CT studies of the shoulder are recommended when patients experience a decrease in range of motion, persistent shoulder pain, or signs of instability. Frequently, patients with rotator cuff tears and peritendinitis calcarea have coexisting abnormalities.

Adolescent↗
PubMed1988

Evaluation of biochemical functions and ventricular performance in regional ischemic-reperfused myocardium by afterload reduction: differential effects of calcium blocking and non-calcium blocking vasodilators.

The effects of afterload reduction with and without calcium blockade on reperfusion injury were studied in the pig. Reversible occlusion of the left anterior descending coronary artery was performed for 60 minutes followed by 120 minutes of reperfusion. For 15 minutes prior to and throughout reperfusion, treatment was administered with a calcium blocker (nifedipine or verapamil), a metallic organic dye and Ca2+ antagonist (ruthenium red), a vasodilator (nitroprusside), or saline. Biochemical functions, i.e., mitochondrial oxidative phosphorylation, myocardial ATP and Ca2+ content, and sarcoplasmic reticulum Ca2+ uptake were determined. Regional left ventricular wall motion was measured echocardiographically. Nifedipine and ruthenium red improved biochemical indices of ischemic myocardium in part by reducing afterload and thereby reducing oxygen demand and in part by reducing calcium entry into cells and mitochondria. Verapamil in the doses used failed to reduce afterload and demonstrated no salutary effect on biochemical parameters in ischemic myocardium. Nitroprusside reduced afterload, improved mitochondrial ATP production and increased percent wall thickening. Our findings suggest that afterload reduction with and without calcium blockade during the early reperfusion phase improves ischemic myocardium. These changes are predominantly biochemical in nature.

Adenosine Triphosphate↗
PubMed1988

Pediatric hand injuries. Types and general treatment considerations.

Growth arrests may occur after fractures, burns, and frostbite injuries, but children generally have a better prognosis from most hand and forearm injuries than adults. Stiffness is less frequent, open wounds heal faster, remodeling of angular deformities may occur, and nerve recovery following repair is significantly better than adults. Parents should be aware of potential problems and the need for follow-up care for evaluating growth and scar development. Perhaps the greatest challenge for nurses as both parents and as members of society is the prevention of traumatic hand injuries. Children should be placed in seat belts when riding in motor vehicles, and toys and play areas should be geared toward the child's developmental age and abilities. Despite careful attention to a child's surroundings, some children will require emergency care for traumatic hand injuries. Health care workers must provide emotional support for parents who may feel guilty about their child's injury. They also must be prepared to give skilled clinical care guided by the child's development and the needs of the family members.

Child↗
PubMed1988

Coagulase-negative staphylococcal endophthalmitis. Increase in antimicrobial resistance.

The predicted sensitivities of common organisms guide initial antibiotic therapy in endophthalmitis. The authors suspected a change in the expected sensitivity of coagulase-negative staphylococci when three cases of endophthalmitis due to multiply resistant organisms failed to respond to intravitreal cefazolin and gentamicin. The authors reviewed 48 cases from 1982 to 1986, compared these with 28 cases from 1973 to 1981, they found increased resistance to gentamicin (35 versus 0%, P less than 0.05) and increased resistance to methicillin (27 versus 19%). Eight cases were resistant to both antibiotics, including the three clinical failures. Final vision was unrelated to antimicrobial resistance. Since cephalosporins may be ineffective clinically against methicillin-resistant staphylococci, concomitant gentamicin resistance may render intravitreal cefazolin and gentamicin inadequate for their treatment. No isolates were resistant to vancomycin. Vancomycin and aminoglycoside, used intravitreally in the initial management of endophthalmitis, would be anticipated to provide better coverage than cefazolin and aminoglycoside for endophthalmitis due to the staphylococci, as well as for infections due to streptococcal and bacillus species.

Aged↗
PubMed1988

Pars plana lensectomy and vitrectomy for complicated cataracts in juvenile rheumatoid arthritis.

Anterior surgical approaches to cataracts in juvenile rheumatoid arthritis (JRA) patients are compromised by chronic anterior and posterior uveitis, miotic pupils, and posterior synechiae. The authors retrospectively reviewed the results of pars plana lensectomy and vitrectomy in ten eyes from seven JRA patients with cataracts associated with chronic iridocyclitis and vitritis. Visual acuities improved from 20/100 or worse preoperatively to 20/60 or better postoperatively. Transient postoperative hypotony lasting 1 week to 4 months occurred in four of the ten eyes. Patients with glaucoma continued to require antiglaucoma therapy after surgery. Pars plana lensectomy and vitrectomy provides a theoretically preferrable approach to complicated cataracts and vitritis in JRA patients because it allows removal of peripheral lens material in the presence of a miotic pupil, eliminates the potential for synechiae to the posterior capsule and/or anterior hyaloid, and clears the visual axis of inflammatory debris.

Adolescent↗
PubMed1988

Applications of a cannulated extrusion needle during vitreoretinal microsurgery.

A specially designed cannulated extrusion needle facilitates the internal drainage of subretinal fluid during vitreoretinal microsurgery. Case histories demonstrate the use of this instrument in the management of complex retinal detachments including eyes with preretinal and subretinal hemorrhage, proliferative vitreoretinopathy with open peripheral retinal breaks, retinal detachment with giant retinal tear, and combined traction-rhegmatogenous detachments due to diabetic retinopathy. This method of internal drainage appears to have specific advantages over standard techniques by allowing the removal of subretinal hemorrhage, the utilization of pre-existing peripheral breaks for internal drainage, and the complete reattachment of shallow posterior pole retinal detachments to allow laser endophotocoagulation.

Adult↗
PubMed1988

Fiberoptic "awake" nasal intubation: physiological and personal concepts.

Use of fiberoptics is gaining in popularity, particularly in neurosurgery. Advantages of use of FNI for the patient with neurological dysfunction include: minimized increases of ICP; decreased use of opiates; reduced manipulation of the spine; direct visualization of the respiratory tract.

Fiber Optic Technology↗
PubMed1988

Effect of splenectomy on exercise-induced pulmonary and systemic hypertension in ponies.

Large increases in systemic and pulmonary arterial pressures of exercising healthy ponies have been observed. Because exercise causes a considerable increase in PCV of ponies, we examined the effect of splenectomy on exercise-induced changes in systemic and pulmonary pressures. These pressures (taken with catheter-tip micromanometers) and indicator dilution cardiac output were determined on 9 healthy ponies that had undergone splenectomy 4 to 9 weeks before the study. Data obtained at rest and during submaximal (10.5 to 11.0 mph) and maximal (14 to 15 mph) exercise from these ponies were compared with similar data from clinically normal ponies. Following splenectomy, PCV increased by only 4 vol% during maximal exercise, but cardiac output of splenectomized ponies reached values similar to those of clinically normal ponies. Despite this similarity in cardiac output, the systemic and pulmonary arterial pressures of exercising splenectomized ponies increased to significantly lower levels than those in clinically normal ponies (P less than 0.01); total pulmonary vascular resistance and total peripheral resistance decreased to values significantly less than those in clinically normal ponies (P less than 0.01). Thus, it appears that increases in blood viscosity induced by increases in PCV may contribute substantially to the pulmonary and systemic hypertension of exercise in clinically normal ponies.

Animals↗
PubMed1987

A tripeptide protease inhibitor attenuates conditioned avoidance behavior.

In a single 10-s training trial, hatchling chicks were conditioned to suppress their spontaneous peck response to a small spherical target by coating it with an aversive liquid. A 24-h test trial employing a dry target demonstrated a robust memory for the training manifested in passive avoidance behavior. Leupeptin, a low-molecular-weight antiprotease, injected i.c.v. 1 h or 15 min prior to training attenuated the long-term avoidance response but not the initial training-induced peck suppression. Leupeptin had no effect on memory if given posttraining. A dose response experiment revealed that a 100- or 200-micrograms dose of leupeptin reliably impaired conditioned avoidance, whereas a 25 or 50-micrograms dose was ineffective. A dipeptide leupeptin analog (L-leucyl-L-arginine) possessed one-half the potency of the tripeptide in the memory task, and a different protease inhibitor (aprotinin) failed to effect the conditioned avoidance behavior. The mechanisms by which leupeptin may exert its influence in this behavioral paradigm and others are discussed.

Animals↗
PubMed1987

Orientation made easy. Using preceptors and skills checklists.

Historically, it has been difficult to list skills that accurately reflect the responsibilities of the perioperative nurse and provide guidance in his or her training. Too often, learning was haphazard, which created inconsistent results and undue stress for new employees. With a preceptor program, the instructor or nurse manager will find improved staff morale and better retention of new employees. Today, ORs are even busier and have more technical equipment than in the past. Uncoordinated teaching efforts by staff and the good intentions of new employees are not enough. Learners must be given every opportunity to be successful. An orientation program that uses adult learning principles, preceptors, and a competency skills list can help new employees quickly become skillful team members.

Clinical Competence↗
PubMed1987

Retinal pigment epithelial cells release inhibitors of neovascularization.

Human retinal pigment epithelial (RPE) cells in culture were found to release a substance (or substances) that causes the regression of new blood vessels on the chick embryonic yolk sac and inhibits proliferation of fetal bovine aortic endothelial cells and human retinal microvessel endothelial cells in vitro. Neither astrocytes nor fibroblasts under identical test conditions released detectable inhibitors of neovascularization or endothelial cell growth. Subconfluent and superconfluent cultures of human RPE cells released higher levels of inhibitor than confluent cultures.

Animals↗
PubMed1987

Differences in learning between hyperprolinemic mice and their congenic controls.

These experiments expanded earlier work on hyperprolinemic mice which showed learning deficits. The following behavioral tasks were used: step-through, passive avoidance; T-maze acquisition; shuttlebox acquisition, and radial-arm maze. Mouse species included PRO/Re-bb (genetically hyperprolinemic mice) and PRO/Re-aa (congenic nonhyperprolinemic controls) obtained from the Jackson Breeding Laboratories. Hyperprolinemic mice were impaired in acquiring T-maze and shuttlebox footshock avoidance behavior. One-trial passive avoidance behavior did not clearly differentiate between the groups. Radial maze performance was poor in both groups due possibly to observed acrophobia and lack of exploratory behavior. The results of this study combined with previously published work suggest that high-brain proline in conjunction with other amino acid changes account for the learning deficits.

Amino Acid Metabolism, Inborn Errors↗